Yes No. Comments 0. Question cannot be greater than characters. Related Questions. Why zinc is not considerd as transition element as it is part of d block? Fix it soon as soon as possible. Latest Preparation questions.
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Question Followers. Report Question. Can be made better Question lacks the basic details making it difficult to answer. Why is cui2 not stable? Is CuI2 unstable? Why is cu2i2 unstable? Does PbI4 exist? Why does PbCl4 exist but not PbI4? Which one does not exist PbCl4? Why NCl 5 does not exist? Why no nf5 and ncl5 exist? Why PBr5 does not exist? Previous Article How does psychology inform education? Next Article What is the role of an art conservator? One of the key features of transition metal chemistry is the wide range of oxidation states oxidation numbers that the metals can show.
It would be wrong, though, to give the impression that only transition metals can have variable oxidation states. For example, elements like Sulfur or nitrogen or chlorine have a very wide range of oxidation states in their compounds - and these obviously aren't transition metals. However, this variability is less common in metals apart from the transition elements. Of the familiar metals from the main groups of the Periodic Table, only lead and tin show variable oxidation state to any extent.
You will find the above examples and others looked at in detail if you explore the chemistry of individual metals from the transition metal menu. There is a link to this menu at the bottom of the page. When a metal forms an ionic compound, the formula of the compound produced depends on the energetics of the process.
On the whole, the compound formed is the one in which most energy is released. The more energy released, the more stable the compound. There are several energy terms to think about, but the key ones are:. The more highly charged the ion, the more electrons you have to remove and the more ionization energy you will have to provide. But off-setting this, the more highly charged the ion, the more energy is released either as lattice enthalpy or the hydration enthalpy of the metal ion.
The formula for Calcium chloride is CaCl 2. Why is that? The overall process is very exothermic. Because the formation of CaCl 2 releases much more energy than making CaCl, then CaCl 2 is more stable - and so forms instead.
What about CaCl 3? This time you have to remove yet another electron from calcium. The first two come from the 4s level. The third one comes from the 3p. That is much closer to the nucleus and therefore much more difficult to remove. There is a large jump in ionization energy between the second and third electron removed. Although there will be a gain in lattice enthalpy, it is not anything like enough to compensate for the extra ionization energy, and the overall process is very endothermic.
It definitely is not energetically sensible to make CaCl 3! The 4s orbital and the 3d orbitals have very similar energies. There is not a huge jump in the amount of energy you need to remove the third electron compared with the first and second.
The figures for the first three ionization energies in kJ mol -1 for iron compared with those of calcium are:. There is an increase in ionization energy as you take more electrons off an atom because you have the same number of protons attracting fewer electrons. However, there is much less increase when you take the third electron from iron than from calcium. The net effect of all this is that the overall enthalpy change is not vastly different whether you make, say, FeCl 2 or FeCl 3.
That means that it is not too difficult to convert between the two compounds. A complex ion has a metal ion at its center with a number of other molecules or ions surrounding it.
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